Fire resistant composite boards and methods

ABSTRACT

Embodiments of the invention provide roofing boards and roofing systems having improved fire resistance properties and methods related to the same. According to one aspect, a roofing system is provided. The roofing system includes roofing panels positioned atop structural support members to form a roof deck. Roofing boards are positioned atop the roof deck and coupled thereto and a roofing membrane is positioned atop the roofing boards and coupled therewith. The roofing boards include a coating of a mineral based material applied to one or more surfaces in an amount between the range of about 0.10 lbs/ft 2  and about 0.70 lbs/ft 2 . The mineral based material coating enables the roofing boards to pass the UL 790 class A tests, such as the burning brand test.

BACKGROUND OF THE INVENTION

Roofing systems often include multiple components that are coupledtogether to perform various functions. For example, roofing systemscommonly include a roof deck, which may be wood or metal, insulationand/or cover boards, and a roofing membrane. The various components maybe coupled via mechanical fasteners, adhesive bonding, ballasting, andthe like. The roof deck often provides a surface upon which the othercomponents are placed and the roofing membrane often provides functionalvalue and/or aesthetic appeal, such as weather proofing the roofingsystem and providing a relatively smooth, flat, and exceptional surface.

An important role of one or more internally located components, such asinsulation and/or cover boards, is to resist the spread of a fire. Theseboards, which are often made of plywood, perlite, polyisocyanurate orother foams, and the like, are often required to pass one or more teststhat are specifically designed to test the board's resistance to fires.One such test is the Underwriters Laboratory 790 Class A tests, whichare based on ASTM E108. One of these tests involves placing a brand atopan assembled roofing system and burning the brand to determine thepresence of fire, ambers, and/or smoke beneath a roof deck. Internalboards often fail this test due to being porous or otherwise allowingair and/or flames to flow to or near a ⅛ inch gap created in the plywoodroof deck. Accordingly, improved roofing boards are needed that are ableto pass this test and/or ensure fire hazard safety.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the invention provide roofing boards having improved fireresistant properties. The roofing boards may have one or more mineralbased coated surfaces or facers that limit air flow through or adjacentthe roofing boards to provide improved fire resistance. The mineralbased coatings enable the roofing boards to pas UL 790 Class A tests,such as the burning brand test.

According to one aspect, a roofing system is provided. The roofingsystem includes a plurality of roofing panels or boards positioned atopand coupled to roofing joists or other structural support members toform a roof deck. A plurality of porous roofing boards or composite foamboards are positioned atop the roof deck and coupled thereto. The porousroofing boards or composite foam boards include a coating of a mineralbased material applied to one or more major surfaces of the boards. Themineral based material is applied in an amount between the range ofabout 0.05 lbs/ft² and 0.70 lbs/ft² in one embodiment, and between about0.10 lbs/ft² and about 0.70 lbs/ft² in another embodiment. The mineralbased material is applied in an amount sufficient to enable the porousroofing boards or composite foam boards to pass the UL 790 class Atests. A roofing membrane is positioned atop the porous roofing boardsor composite foam boards and coupled therewith. According to oneembodiment, the porous roofing boards or foam composite foam boards mayinclude a glass fiber mat coupled with a major surface of the respectiveboard. The glass fiber mat may be saturated with the mineral basedmaterial.

According to another aspect, a roofing board is provided. The roofingboard includes a mineral based material coating on one or more majorsurfaces of the roofing board. The mineral based material coating mayhave a coating weight of at least 0.10 lbs/ft² that enables the roofingboard to pass the UL 790 class A tests.

The roofing board may include a glass mat facer applied to one or moremajor surfaces and the mineral based material may be applied to theglass mat facer. In some embodiments, the roofing board includes twoglass mat facers applied on opposite major surfaces of the roofingboard. In such embodiments, a first glass mat facer may have a coatingweight of at least 0.10 lbs/ft² of the mineral based material (morecommonly at least 0.14 lbs/ft² of the mineral based material) and asecond glass mat facer may have a coating weight of less than 0.10lbs/ft² of the mineral based material (often less than 0.12 or 0.14lbs/ft² of the mineral based material). The first glass mat facer mayhave a first glass mat weight and the second glass mat facer may have asecond glass mat weight that is less than the first glass mat weight. Insome embodiments, the glass mat facer may have a weight of at least 1.4lbs/100 ft², and more commonly about 2.1 lbs/100 ft². In otherembodiments, such as those involving the use or perlite board, the glassmat may have a weight of about 0.9 lbs/100 ft² or more.

The mineral based material may include a composition having betweenabout 25% and 50% water and between about 50% and 75% solid materials.The solid material composition may include a combination of a firstfiller material and a second filler material. The first filler materialmay include one or more of: calcium carbonate, perlite, clay, gypsum,and the like; and the second filler material may include one or more of:clay, mica, talc, perlite, expanded perlite fines, flumed silica, flyash, fiber glass, vermiculite, titanium dioxide, zinc oxide, and thelike.

The mineral based material coating may have a coating weight of at least0.14 lbs/ft² in some embodiments. In other embodiments, the mineralbased material coating may have a coating weight of between about 0.18lbs/ft² and about 0.21 lbs/ft². These coating weight ranges may bepreferred for embodiments involving foam based roofing boards. In otherembodiments, such as those involving perlite roofing boards, the mineralbased material coating may have a coating weight of 0.05 lbs/ft² ormore. In an exemplary embodiment, the mineral based material coating ofa perlite roofing board may have a coating weight of between about 0.11lbs/ft² and 0.18 lbs/ft². In some embodiments, the mineral basedmaterial may include calcium carbonate and an acrylic binder and may ormay not include a fire retardant additive.

The roofing board may be between about ¼ inch thick and 6 inches thickdepending on the need and/or required usage. The roofing board may alsohave a density of between about 1 Lb/ft³ and about 15 lbs/ft³. Theroofing board may be composed of one or more of the following materials:wood fibers, perlite, polyisocyanurate, polystyrene, extrudedpolystyrene, cellular glass, gypsum, cement boards, magnesium oxide,pressed recycled paper, particles, and the like. In specificembodiments, a foam roofing board may have a density between about 1.5lbs/ft³ and 12 lbs/ft³, although densities within the range of 1.5lbs/ft³ and 8 lbs/ft³ are more common. Similarly, a perlite roofingboard may have a density range of between about 8 lbs/ft³ and 30lbs/ft³, although a range of between 9 lbs/ft³ and 18 lbs/ft³ is morecommon. Further, a wood roofing board may have a fiber density rangebetween about 15 lbs/ft³ and 25 lbs/ft³. Gypsum, cement, mag oxide, andthe like typically have density ranges higher than those listed.

According to another aspect, a composite perlite roofing board isprovided. The composite perlite roofing board includes a composite corematerial having roughly between 40% and 70% of expanded perlite, between30% and 60% of paper products (may be recycled paper products), between1.5% and 10% of a starch binder, and between 1.0-1.5% and 5% asphalt. Aglass mat facer is coupled with one surface of the composite core toreinforce the composite perlite roofing board. The glass mat facer mayhave a mat weight of between about 0.9 and 3.0 lbs/100 ft² in oneembodiment, and a mat weight of between about 1.4 and 2.0 lbs/100 ft² inanother embodiment. The glass mat facer reinforcement may strengthen thecomposite perlite roofing board so as to help prevent wind uplift and/orfor various other reasons.

In some embodiments, a mineral based coating material may be applied tothe glass mat facer. The mineral based coating material may enable thecomposite perlite roofing board to pass the UL 790 Class A tests. Theglass fiber mat may have a mat weight of at least 0.9 lbs/100 ft² in oneembodiment, and at least 1.4 lbs/100 ft² in another embodiment, and themineral based material coating may have a coating weight of at least 8to 15 lbs/100 ft² in one embodiment, 10 to 12 lbs/100 ft² in anotherembodiment, and more commonly about 12 lbs/100 ft².

According to another embodiment, a method of manufacturing a roofingboard is provided. According to the method, a roofing board may beprovided and a mineral based material may be applied to at least onemajor surface of the roofing board. The mineral based material may beapplied so that the roofing board has a coating weight of at least 0.10lbs/ft². The mineral based coating may enable the roofing board to passthe UL 790 class A tests, which is otherwise difficult with similarconventional roofing boards.

According to one embodiment, a glass mat may be applied to or coupledwith at least one major surface of the roofing board so that the majorsurface is faced with the glass mat. The mineral based material may beapplied to the faced glass mat surface of the roofing board. In someembodiments, a second glass mat may be applied to the other majorsurface of the roofing board so that both major surfaces of the roofingboard are faced with a glass mat. A coating may also be applied to theother faced glass mat surface of the roofing board (i.e., to the secondglass mat). The coating may be applied so as to have a coating weight ofless than 0.10 lbs/ft². Stated differently, the first glass mat andsecond glass mat may have different coating weights and/or coatingmaterials. The faced glass mat surface having a coating weight of atleast 0.10 lbs/ft² may be positioned with respect to a roof deck so asto face the roof deck.

According to another aspect, a method of manufacturing a roofing boardis provided. The method may include applying a mineral based material toa glass mat having a mat weight of at least 1.4 lbs/100 ft². The mineralbased material may be applied so that the glass mat includes a coatingweight of at least 0.10 lbs/ft². The method may also include pouring afoam material over the coated glass mat, or laminating a foam core withthe coated glass mat, wherein the foam material forms the roofing board.The method may further include applying a second coated glass mat to anopposite surface of the foam roofing board so that the foam roofingboard is sandwiched between two coated glass mats. The second coatedglass mat may have a mat weight less than the other or first coatedglass mat.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in conjunction with the appendedfigures:

FIG. 1 illustrates a roofing system according to an embodiment of theinvention.

FIGS. 2A-C illustrate roofing boards that may be used in the roofingsystem of FIG. 1 according to embodiments of the invention.

FIGS. 3A-E illustrate a setup for Underwriters Laboratory 790 class Aburning brand test according to an embodiment of the invention.

FIGS. 4A & B illustrate graphs showing the improved strength propertiesof a roofing board having a glass mat facer according to an embodimentof the invention.

In the appended figures, similar components and/or features may have thesame numerical reference label. Further, various components of the sametype may be distinguished by following the reference label by a letterthat distinguishes among the similar components and/or features. If onlythe first numerical reference label is used in the specification, thedescription is applicable to any one of the similar components and/orfeatures having the same first numerical reference label irrespective ofthe letter suffix.

DETAILED DESCRIPTION OF THE INVENTION

The ensuing description provides exemplary embodiments only, and is notintended to limit the scope, applicability or configuration of thedisclosure. Rather, the ensuing description of the exemplary embodimentswill provide those skilled in the art with an enabling description forimplementing one or more exemplary embodiments. It being understood thatvarious changes may be made in the function and arrangement of elementswithout departing from the spirit and scope of the invention as setforth in the appended claims.

Embodiments of the invention provide fire resistant roofing boards andmethods for manufacturing or producing the same. According to someembodiments, the roofing board may be made of a foam composite materialor a porous material. The roofing boards enable a roofing system to passthe Underwriters Laboratory 790 Class A test, which is also sometimescalled the UL 790 Class A test over a combustible roof deck, UL 790Class A burning brand test, and the like, which is based on ASTM E108(hereinafter the UL 790 Class A burning brand test or simply the burningbrand test). The test protocol typically requires the following, 1)Spread of Flame, 2) Intermittent Flame and 3) Burning Brand tests. Thelatter two tests often use a wood deck that contains three pieces ofplywood fastened to a wood frame with ⅛ inch gaps between plywoodjoints. The Spread of Flame test uses one sheet of plywood with no gaps.

The UL 790 Class A burning brand test is depicted in FIGS. 3A-3E. Theroof system to be tested is placed on top of a plywood deck 312 andframe 302 and the cover board 322 or underlying insulation is cut into 3pieces and joints 324 are offset (e.g., 6 inches) from the plywoodjoints 312 as shown in FIG. 3D. Fasteners (not shown) are used atcorners of roofing boards to hold in place. Frame 302 is typicallyconstructed from 2×4 inch wood posts. Plywood deck 312 is attached toframe 302 with ⅛ inch gaps 314 between adjacent plywood boards as shownin FIG. 3B. Cover board 322 is attached atop plywood deck 312 withadjacent cover boards pieces butted together and joints 324 offset fromjoints 314. In another embodiment, polyisocyanurate foam insulationboards (polyiso boards) may be used instead of the cover board 322. Thepolyiso boards may be a foam density of about 1.5 to 2.0 pcf, and may bebetween about ¼ to 6 inch thick. In yet another embodiment a polyisofoam cover board may be used having a foam density of between about 4 to8 pcf (commonly for polyiso boards having a thickness of % to ½ inch).For ease in described the embodiments, these and other boards will begenerally referred to as cover boards 322. The brand 332 is typicallyplaced atop the cover boards 322. To pass the burning brand test, thebrand 332 must be 100% consumed with no flame visible on underside ofwood roof deck 312 at any point during the test. The test will continueas long as smoke and/or ambers are present.

The plywood joints 314 and roofing board joints 324 present a challengefor porous roofing boards or foam composite boards with thinner orporous facers that do not provide sufficient fire resistance andresistance to air flow from the ⅛ inch plywood joints 314. In order topass the burning brand test, the roofing board must often resistshrinkage under extreme heat and provide a barrier to prevent flame frompenetrating the wood roof deck 312, especially at the ⅛ inch joints 314.For conventional porous and foam composite boards, failure typicallyoccurs before the brand is fully consumed with a flame appearingunderneath the wood deck at the joint 314.

According to one embodiment, porous or composite fire resistant boardsare described. The porous boards include a mineral based coating thatlimits the amount of air flow through the board to a roof deckpositioned under the porous boards. The limited air flow may allow theboards to pass the UL 790 Class A burning brand test. The porous boardsmay be fibrous boards that usually fail the burning brand test even whena fire retardant material is used with the board. Conventional boardsusually fail due to the high passage of air through or approximate tothe board. For example, with conventional boards, gaps may form betweenthe boards and the roof deck, which may provide a clear path for fire topenetrate to the underlying roof deck.

According to one embodiment, a fire resistant porous board may include aperlite board having a composition of roughly 40-70% expanded perlite,30-60% recycled paper products, 1.5-10% starch binder, 1.0-5% asphalt,and the like. The fire resistant porous board may be between about ¼inch and 3 inches, although ½ to 1.5 inches is more common, and may beused as a roofing cover board, a roofing recover board, a fire resistantroof substrate over roof decks, and the like. Fire resistant roofsubstrates typically require significantly improved fire resistance overother cover board and often must be able to pass UL 790 Class A test.The plywood joints and roofing board joints often present a challengefor porous roofing boards, such as perlite based cover boards, since aircan flow through plywood joints to feed fire above. Conventionalperlite, cellulose, or wood fiber based cover boards often cannot passthe Class A burning brand and/or intermittent flame tests. With perlitebased cover boards, failure often first occurs at the plywood jointswhere flames penetrate through the board and appear underneath the wooddeck within the plywood joints.

For example, with a ½ inch thick perlite board, Class A burning brandtest failure usually occurs within 10 to 15 minutes when the brand isonly approximately 50% consumed. Although perlite boards are often fireresistant due to a high expanded perlite content, they are porous andallow air to permeate through the board which helps fuel fire on top ofthe board from spaces or areas underneath, thereby acceleratingpenetration of a flame through the board and gaps in the wood deck.

Embodiments of the invention improve the fire resistance of perlite andother porous boards as required for the UL 790 Class A tests. The fireresistance of these boards is improved by minimizing air flow throughthe board from gaps in the underlying wood deck. According to oneembodiment, the air flow is minimized by coating the porous boards witha mineral based material, which may be a relatively inexpensivematerial. The mineral based coating may provide sufficient resistance toair permeation, thereby suffocating a fire as it penetrates through theboard during the burning brand and intermittent flame tests.

In one embodiment, the mineral based coating is only applied to one sideof the board. The coated side is then oriented towards the wood deck sothat the coating layer bridges the plywood joints, thereby suffocatingthe fire above. In another embodiment, both sides of the board arecoated with the mineral based material, which may further suffocate afire. The mineral based coating materials are often relatively heatand/or fire resistant. Exemplary mineral based materials include calciumcarbonate, clay, perlite, fiber glass, silica, fly ash, ceramic spheres,cement, gypsum, and the like.

Porous boards coated with such materials in the manner described hereinachieve significant improvements in fire resistance as measured byburning brand and intermittent flame tests. For example, with a calciumcarbonate based coating using a sodium silicate binder, a ½ inch perliteboard containing approximately 40% cellulose fiber was able to pass theburning brand test with approximately 0.1 lbs/ft² of coating (e.g., 3.2lbs per a 4 foot by 8 foot board). Similarly, using a cementitouscoating, 0.2 lbs/ft² also enabled a coated ½ inch perlite board to passthe burning brand test.

According to one embodiment, the addition of fire retardants (e.g.,sodium borate, aluminum trihydrate, and the like) in the coating mayreduce the coat weight needed for the porous boards to pass the UL ClassA tests. The addition of such fire retardants, however, is not neededand may add additional and unneeded expense.

According to some embodiments, the mineral based material coatings canbe spray applied or metered onto the porous boards at desired weightand/or thicknesses. The coatings can be reinforced with glass fibers andadditional binders to improve mechanical properties of the board and tomitigate cracking when using heavier coatings.

For convenience, the porous boards described herein will be generallyreferred to as perlite boards. It should be realized, however, that theporous boards embodied herein are not limited to perlite boards, but mayinclude virtually any porous board. Examples of other porous boards thatmay be coated with a mineral based material to improve the fireresistance of such boards include boards having various compositions ofwood fibers, perlite, cellular glass, pressed recycled paper, particleboard, and the like.

According to another embodiment, the porous board may include a facermaterial that improves the strength characteristics of the board.Roofing cover boards are often subjected to wind loads and must meetspecific wind resistance performance criteria, such as those dictated byFactory Mutual and other building code agencies. An exemplary board mayinclude a perlite/fiber core with an outer facing consisting of anon-woven mat and/or scrim adhered to the perlite/fiber core. The outerfacing may improve the strength of the board and/or other properties ofthe board. For example, the outer facing may improve the wind upliftresistance of the board and/or tensile (flexural) strength of the boarddue to the high tensile strength of the outer facing. The outer facingmay include a plurality of intermeshed glass fibers. According to oneembodiment, the glass fiber mat or scrim may have a weight of betweenabout 0.5 lbs/100 ft² and about 4 lbs/100 ft², although a mat/scrimweight of between about 0.9 lbs/100 ft² and 3 lbs/100 ft² is morecommon.

As described previously, the porous board may have a composition ofroughly 40-70% expanded perlite, 30-60% recycled paper products, 1.5-10%starch binder, 1.0-5% asphalt, and the like. The porous board istypically between about ¼ inch and 4 inches in thickness, although ½ to1.5 inches is more common. The perlite core may also include variouswood fibers, soluble fibers, or other types of fibers. As describedpreviously, the board may be used as a roofing cover board, roofingrecover board, insulation and/or fire resistant roof substrate for roofdecks, and the like.

According to one embodiment, the outer facer (e.g., glass fibermat/scrim) may be coated with the mineral based material describedherein. The mineral based coating may provide the fire resistantproperties described herein. Thus, the resulting board may include acombination of improved strength properties and fire resistantproperties. The use of the outer facer may reduce the amount of mineralbased material that needs to be applied by providing a relatively flatand/or smooth outer surface. In some embodiments, the overall weight ofthe resulting board may be reduced by using the outer facer and reducedmineral based coating. The glass mat or scrim may provide structuralsupport to the mineral based material coating by preventing the boardfrom significantly shrinking during the UL Class A burning brand test.

In some embodiments, improved fire performance can be achieved byreducing the fiber content in the board's core, increasing the glass matweight, and/or increasing the coating weight. Further, fire retardantscan be used in the mineral based coating to further enhance fireresistance, although such additives are not needed and not included invarious embodiments.

According to another embodiment, a foam core roofing board havingimproved fire resistant properties is provided. The foam core roofingboard (hereinafter foam roofing boards or foam composite boards)includes one or more outer facers that are heavily coated with themineral based material described herein. These heavily coated facersallow the foam roofing boards to pass the UL Class A burning brandtests.

Conventional foam boards typically include light facer materials thatroutinely fail the UL Class A burning brand tests. These conventionalfoam boards often fail the burning brand test 10 to 20 minutes prior tothe brand being fully consumed. The mode of failure is typically theformation of large gaps between the foam composite boards and theunderlying facer that is in contact with the wood or metal roof deck.Stated differently, gaps begin to form between the roof deck and thefacer material. These gaps provide a clear path for fire and/or air topenetrate to the ⅛ inch plywood joint and through these joints to theunderlying roof deck. Typically, once the bottom facer fails at or nearthe plywood joint, air fuels the fire and flames develop underneath thewood deck resulting in a failure of the UL Class A burning brand test.The formation of such gaps is limited or minimized with the heavilycoated facer of the foam composite boards described herein, thusallowing these boards to pass the UL Class A burning brand test. Gapformation may be minimized as a result of the heavily coated facerminimizing the shrinkage of the foam composite board when exposed to thefire's heat and/or flame.

According to one embodiment, a foam composite board includes apolyisocyanurate foam core having a density of between about 1.5 and 12lbs/100 ft³. The thickness and/or density of the foam may be varieddepending on the ultimate use of the foam composite board. For example,¼ to ½ inch thick boards can be produced with high foam densities (e.g.,commonly 4 to 8 lbs/100 ft³, although densities of up to 25 lbs/100 ft³are possible) for cover board applications where impact resistance isrequired. Alternatively, lower density and thicker foam boards (e.g., ½to 4 inches) with higher R values may be used for insulation purposes.

The polyisocyanurate foam core may be faced on one or both sides with aglass mat, which may be coated with a relatively light or heavy mineralbased coating. The heavy coating may include coatings having a coatingweight of at least 10 lbs/100 ft² (i.e., 0.10 lbs/ft²). The lightcoating may be any coating having a coating weight of less than 10lbs/100 ft² (i.e., less than 0.10 lbs/ft²). In some embodiment, theheavy coating weight may be anything more than about 5 lbs/100 ft²(i.e., 0.05 lbs/ft²). According to another embodiment, the heavy coatingincludes any coating weight of 14 lbs/100 ft² (i.e., 0.14 lbs/ft²) ormore. The weight and/or thickness of the glass mat may also be increasedcompared with conventional foam composite boards.

According to one embodiment, the foam composite board includes only asingle heavily coated facer, which is typically placed in contact withthe roof deck. The heavily coated facer minimizes the formation of gapsby limiting the amount of shrinkage the foam composite board experienceswhen exposed to a fire's heat and/or flame, thus suffocating a fireabove. These foam composite boards may include conventional light coatedglass facers on a top surface. According to another embodiment, the foamcomposite board includes two heavily coated facers. The heavily coatedfoam composite boards may not require the use of a fire retardant,although a fire retardant may be used in some embodiments, which mayreduce the amount of the mineral based material that needs to beapplied. In another embodiment, the foam composite board and heavilycoated facer may be placed over underlying insulation and still pass theburning brand test.

Having described several embodiments, additional aspects of theinvention will be more evident with reference to the figures. Referringnow to FIG. 1, illustrated is a roofing system 100 that may be placedatop a building or other structure. System 100 includes a roof deck 102,which may include a plurality of roofing panels or boards that arepositioned atop roofing joists or other structural support members andcoupled thereto. The roofing panels/board, and thus the roof deck 102,may be made of various wood boards, corrugated metal, plywood, orientedstrand board (OSB), concrete, reinforced concrete, and the like. Manybuildings include metal or corrugated metal roof decks, such as 18 to 22gauge steel. As described herein, the UL 790 Class A test typically usesplywood boards to simulate a roof deck.

A plurality of roof insulation type boards 110 are typically positionedand arranged atop roof deck 102. The roofing insulation board 110 may becomposed of various fiber materials, foam materials, and the like, andmay be selected based on a thermal resistance (R Value) provided,compressive and/or other strength provided, and the like. Commoninsulation boards 110 include wood fiber board, perlite boards,polyisocyanurate foam boards, expanded polystyrene foam boards, extrudedpolystyrene foam boards, cellular glass boards, gypsum boards, and thelike. The insulation boards 110 are typically between about ¼ inch and 6inches thick or more depending on insulation needs and other needs.

The insulation board 110 may be coupled with roof deck 102 viamechanical fasteners 104, via ballasts (not shown), via adhesivebonding, and the like. Although not common, in some embodiments, system100 may not include insulation board 110. In some embodiments, a vaporbarrier (not shown) may be applied to the roofing deck 102 between thedeck and the insulation boards 110.

According to some embodiments, a plurality of cover boards 106 mayoptionally be positioned atop the insulation boards 110. The coverboards 106 are often thinner and/or denser boards than the insulationboards 110 that provide a relatively flat surface to which roofingmembranes 108, wood or asphalt shingles, and the like may be attached.The density of the cover boards 106 may vary based on the material used.For example, cover boards comprising gypsum, wood fiber, OSB, and thelike, are typically considerably denser than the insulation boards.Cover boards 106 typically are boards that are designed to provide aprotective layer for the insulation boards 110 while coupling with aprotective outer layer, such as the roofing membrane 108 or roofshingles. Exemplary cover boards include OSB, plywood, perlite, highdensity foam boards (e.g., polyisocyanurate), and the like. The coverboard 106 may be coupled with insulation board 110 and/or roof deck 102via mechanical fasteners 104, via ballasts (not shown), via adhesivebonding, and the like.

In some embodiments, system 100 includes either the insulation boards110 or cover board 106, but not both. In yet other embodiments, thearrangement of the cover board 106 and insulation board 110 may bereversed so that the insulation boards 110 are positioned atop the coverboards 106. Various configurations are possible depending on the needand specific roofing application.

A roofing membrane 108 may be coupled with a top surface 112 of coverboard 106 or insulation board 110. The roofing membrane 108 may protectthe underlying roofing layers, such as by sealing the layers from rainand other environmental factors, and/or may provide other functional oraesthetic purposes. For example, the roofing membrane 108 may provide abrilliant white aesthetically pleasing look and may reduce urban heatisland effects by reflecting radiation. According to one embodiment, theroofing membrane 108 may be made of polyvinyl chloride (PVC),thermoplastic polyolefin (TPO), ethylene proplylene diene monomer rubber(EPDM), bitumen, and the like. Roofing membrane 108 may be mechanicallyfastened, ballasted, adhered, and the like, to the top surface 112. Acommon method of coupling adjacent roofing membranes 108 includes heatwelding the adjacent membranes. According to another embodiment, theroofing shingles may be coupled with top surface 112 instead of roofingmembrane 108.

According to one embodiment, the insulation board 110 and/or cover board106 may include a coating of a mineral based material applied to one ormore major surfaces. As used herein, the term “major surface” means arelatively large and often relatively flat surface of the board. Forexample, a roofing board typically has two large and relatively flatsurfaces (i.e., the top and bottom surfaces) that are bordered by smalledge surfaces. The mineral based material coating may limit thepenetration of air and/or flame through the insulation board 108 and/orcover board 106 so as to resist the spread of a fire through the roofsurface. According to one embodiment, the coated surface may bepositioned directly above and adjacent the roof deck 102 to limit theflow of air and/or the spread of a flame directly above the roof deck102. Stated differently, the mineral based material coating may bepositioned directly adjacent the roof deck 102.

In another embodiment, both major surfaces of the insulation board 110and/or cover board 106 may include a mineral based material coating tofurther restrict air flow and/or a flame spread through the coatedboard. Typically either the insulation board 110 or cover board 106includes the mineral based coating, but in some embodiments both boardsmay include the mineral based coating on one or more surfaces. Further,as described above, cover board 106 may be positioned directly adjacentroof deck 102 in some embodiments. Accordingly, a coated surface ofcover board 102 may be positioned directly adjacent roof deck 102.

The mineral based material being applied to the insulation board 110and/or cover board 106 in an amount ranging between about 0.05 lbs/ft²and about 0.50 lbs/ft², although a minimum amount of about 0.10 lbs/ft²,and a range of between about 0.10 lbs/ft² and 0.30 or 0.20 lbs/ft² ismore common. The mineral based material coating is sufficient to enablethe coated insulation board 110 and/or cover board 106 to pass the UL790 class A tests, and especially the burning brand test. Conventionalinsulation boards and cover boards, which may include light materialcoatings, often fail these tests early in the testing process due to therelatively high air flow through, or with respect to, the boards and dueto the accompanying flame spread. Air flow through or with respect tothe conventional boards may be due to the porosity of the boards,shrinkage from heat and/or flame exposure, and the like. The abovedescribed coating ranges adequately restrict airflow through or withrespect to the boards to allow the boards to pass these tests.

According to some embodiments, the coated insulation boards 110 and/orcover boards 106 may also include a nonwoven facer that may be coatedwith the mineral based coating in the described amounts. The nonwovenfacer may strengthen and/or reinforce the boards. According to oneembodiment, the nonwoven facer may include glass fibers and may have amat weight of between about 0.9 lbs/100 ft² and 4.0 lbs/100 ft²,although a mat weight of between about 1.4 lbs/100 ft² and 2.0 lbs/100ft² is more common. The glass fiber mat facer may be coated with themineral based coating to both reinforce the board and provide the fireresistant properties described herein.

Referring now to FIG. 2A, illustrated is an embodiment of a roofingboard 200 having improved fire resistant properties. Roofing board 200may be an insulation board 110 or a cover board 106 as previouslydescribed. In one embodiment, roofing board 200 is a porous board thatmay include a core 202 of various compositions of wood fibers, perlite,cellular glass, gypsum, cement boards, magnesium oxide, pressed recycledpaper, particle board, and the like. For ease in describing thisembodiment, roofing board 200 will be generally referred to as a perliteboard 200.

Perlite board 200 may have a composition of roughly 40-70% expandedperlite, 30-60% recycled paper products, 1.5-10% starch binder, 1.0-5%asphalt, and the like. Perlite board 200 may also have a thickness ofbetween about ¼ inch and 3 inches depending on whether the board is tobe used for insulation, protective, or other purposes. Perlite board 200also includes a mineral based coating on one or both major surfaces,which coating is impervious enough to limit the amount of air flowthrough the board to a roof deck positioned below the perlite board andallow the perlite board 200 to pass the UL 790 Class A burning brandtest as described herein. The mineral based material may be applied as acontinuous layer of material to suffocate a fire. According to oneembodiment, a bottom surface of perlite board 200 that is positionedadjacent a roof deck includes the mineral based coating. In otherembodiments, a top and bottom surface of the perlite board 200 mayinclude the coating.

The mineral based material may be applied as a continuous layer in anamount ranging between about 0.05 lbs/ft² and about 0.70 lbs/ft²,although a range of between about 0.10 lbs/ft², and 0.20 lbs/ft² is morecommon. Exemplary mineral based materials include calcium carbonate,clay, perlite, fiber glass, silica, fly ash, ceramic spheres, cement,gypsum, and the like. Table 1 below provides a non-limiting exemplarymineral based coating formulation.

TABLE 1 Exemplary mineral based coating formulation. Range (w %) CoatingComponents (wet basis) Water 25 to 50 Increase water to reduce coatweight Total Solids 50 to 75 Increase solids to increase coat weight,board strength and fire resistance Composition (w % of total solids, drybasis) Primary Fiber 44 to 94 CaCO3, Perlite, Clay, Gypsum, etc.Secondary Fiber  0 to 20 Clay, Mica, Talc, Expanded Perlite Fines, FumedSilica, Fly Ash, Fiber Glass, Vermiculite, Titanium Dioxide, Zinc,Oxide, etc. Fire Retardant  0 to 20 Borax, ATH, etc. Sodium Silicate  5to 10 Latex 1 to 5 Compatible with sodium silicate Thickener   0 to 0.5xgum, HEC, CMC, associative thickener, etc.

As shown in Table 1, the mineral based material may include one or morefiller materials and/or other additives that are mixed with water. Aprimary component of the mineral based material may be calciumcarbonate, perlite, clay, gypsum, or similar materials. In someembodiments, the mineral based material may include a high percentage(e.g., approximately 90% or so) of calcium carbonate that is mixed withlatex (e.g., 6%) and/or sodium silicate. According to a non-limitingspecific embodiment, the mineral based material may includeapproximately 40% water and 60% solids, which consists of a combinationof approximately 93% calcium carbonate, 6% sodium silicate, and 1%latex. This combination was found to be effective at providing asubstantially impervious coating layer.

The mineral based material may also include an acrylic binder and may ormay not include a fire retardant. According to some embodiments, themineral based material may provide improved fire resistant propertieswithout including a fire retardant. The addition of a fire retardant(e.g., sodium borate, aluminum trihydrate, and the like) in the coatingmay reduce the coat weight needed for the porous boards 200 to pass theUL Class A tests. However, the addition of such fire retardants is notneeded and may be eliminated to reduce additional costs.

According to some embodiments, the mineral based material coatings canbe spray applied or metered onto the perlite or porous boards 200 atdesired weight and/or thicknesses.

Referring to FIG. 2B, illustrated is an embodiment of a compositeroofing board 220 having a core layer 222 reinforced with a nonwovenfiber mat 224. Nonwoven fiber mat 224 may enhance the mechanicalproperties of roofing board 220, such as by improving the tensilestrength and/or wind uplift strength, and/or may mitigate cracking whenthe nonwoven fiber mat 224 is coated with a mineral based coating asdescribed herein. Core layer 222 may be a porous board having a similarcomposition and configuration (e.g., thickness) to roofing board 200.The composition and configuration of core layer 222 may be selectedbased on need and/or application, such as if the board is being used forinsulative or protective purposes and the like.

According to one specific embodiment, core layer 222 may be a perliteroofing board and may be reinforced with a glass fiber mat 224.Conventional perlite roofing boards do not include glass fiber matfacers due to difficulties in bonding the materials and the like. Thereinforcing glass fiber mat 224 may have a mat weight ranging betweenabout 0.9 lbs/100 ft² and 3.0 lbs/100 ft², although a mat weight ofbetween about 1.4 lbs/100 ft² and 2.0 lbs/100 ft² is more common. Matweight of greater than 3.0 lbs/100 ft² may likewise be used, but areoften not desired due to the increased weight. Similarly, mat weightsless than 1.0 lbs/100 ft² may be used, but are often not desired due toa decrease in mat reinforcing properties. Although not shown, roofingboard 220 may also include one or more other layers, such as a scrimlayer.

The roofing board 200 may or may not include a mineral based coatingapplied to the glass fiber mat 224. In some embodiments, a binder otherthan the mineral based material may be used. The mineral based materialmay have a composition similar to that previously described and may beapplied to the glass fiber mat 224 as a continuous layer in an amount ofabout 0.05 lbs/ft² or more. The glass fiber mat 224 may provide arelatively smooth continuous surface compared with a conventionalperlite board, which may allow less of the mineral based material to beapplied. For example, according to one embodiment, a coating weight ofabout 0.05 lbs/ft² is applied to a glass fiber mat having a mat weightof about 1.0 lbs/100 ft². According to another embodiment, a coatingweight of about 0.10-0.11 lbs/ft² is applied to a glass fiber mat havinga mat weight of about 1.4 lbs/100 ft². According to yet anotherembodiment, a coating weight of about 0.20-0.22 lbs/ft² is applied to aglass fiber mat having a mat weight of about 2.0 lbs/100 ft². As can bereadily understood, the heavy mat weights typically require a heaviermineral based material coating and, thus, mat weights of greater thanabout 2.0 lbs/100 ft² may not be desired due to the increased weight andcost of the resulting roofing board.

The glass fiber mat facer 224 greatly increases the overall strength ofthe perlite board 220. For example, as shown in FIG. 4A, a glass fibermat 224 reinforced perlite board 220 (F1 and F2) exhibits a 300-400%increase in break load when compared with conventional perlite boards(Ctrl). Similarly, as shown in FIG. 4B, glass fiber reinforced perliteboards exhibit approximately 300% or more increase in fastener pullthrough strengths when compared with conventional perlite boards. FIG.4B illustrates 3 perlite boards that include a mineral based coatinghaving a coating weight ranging between 110 g/ft² and 250 g/ft²,although a significant improvement is not evident between the differentcoating weights.

According to one embodiment, the reinforced perlite board 220 may bemanufactured by applying the mineral based coating or another adhesiveto the perlite board and glass fiber mat. Rollers or other means maythen press the glass fiber mat into the perlite board. Dryers may thenbe used to quickly set the coating/adhesive so that the glass fiber matdoes not separate from the perlite board when handled. According to someembodiments, the mineral based coating may not provide any wet strengthor bond when wet, thus drying may be required immediately after pressingthe glass fiber mat into the perlite board.

In some embodiments, the perlite boards may be formed with a Fourdrinierprocess in 12 foot widths and then dried in a gypsum type dryer. Due tothe low strength of wet perlite board entering the oven and the amountof water removed from the perlite board, the application of the glassmat normally occurs after the board exits the dryer and is cut to anapproximate width of about 4 feet. The glass fiber mat may then beapplied in a finishing process after the perlite board manufacturingprocess, in which slightly over sized perlite boards (e.g., 4 foot by 8foot) are butted together for continuous application of the glass fibermat and mineral based, or other adhesive, coating on one or both sidesof the perlite board. The mineral based or adhesive coating may besprayed or metered onto the perlite board surface. Once the glass fibermat is applied and the coating is dried, the continuous length of boardmay be cut to length, such as with a cross cut saw and/or gang saw.

In some embodiments, a foam board manufacturing facility (e.g.,polyisocyanurate facility) may be retrofit to manufacture the perlitereinforced board by adding de-stacking capabilities, coating/adhesiveapplicators, pressing and drying sections between the facer unwind andlaminator, and the like. Sufficient drying capacity would likely beneeded to set the coating/adhesive prior to entering the laminator. Thelaminator could be retrofit with compressible belts to apply uniformpressure to the perlite board and produce gaps between metal slats toallow for additional drying. Existing saws and stacking equipment may beused to trim boards to correct dimensions and package. According to thisembodiment, the perlite boards may be cut slightly oversized at theperlite plant and shipped to the foam manufacturing facility forsubsequent application of glass fiber mat.

The perlite reinforced boards described herein may provide both strengthreinforcement and fire resistant properties. A specific non-limitingapplication of the perlite reinforced board is in resisting wind upliftforces that a roofing surface may experience. The board may alsosuffocate a fire as described herein. As shown in FIG. 2C, in someembodiments, the reinforced perlite roofing boards may have glass fibermats applied to both major surfaces. One or both of these glass fibermats may be coated with the mineral based material described herein.

Referring now to FIG. 2C, illustrated is another embodiment of a roofingboard 240 having improved fire resistance properties. Roofing board 240include a core material layer 242 sandwiched between two nonwoven facermaterial layers 244 & 246. The core material layer 242 may be any of thepreviously described roofing boards, such as perlite, gypsum, woodfibers, and the like. In a specific embodiment, core material layer 242may be a foam material, such as polyisocyanurate, polystyrene, expandedor extruded polystyrene, and the like (referred to hereinafter as foamboard 242 for convenience). One or both of the outer facer layers, 244 &246, may be coated with the mineral based material described herein. Ina specific embodiment, a bottom facer 246 of roofing board 240 mayinclude a heavy coating of the mineral based material, while a top facer244 include a lighter coating of the mineral based material or anothermaterial. The heavily coated bottom facer 246 may be positioned directlyatop and adjacent a roof deck (not shown).

Foam board 242 may have a density of between about 1.5 and 12 lbs/100ft³ (pcf), although densities between about 1.5 and 8 lbs/100 ft³ aremore common. In some embodiments, a foam density of up to 25 lbs/ft³ ispossible, but may be less economically feasible. The thickness and/ordensity of the foam may be varied, typically between about ¼ inch and 6inches, depending on the required use and/or application of the foamboard 242. For example, ¼ to ½ inch thick high density boards can beproduced for cover board applications where impact resistance and otherprotective properties are needed. Alternatively, lower density andthicker foam boards (e.g., ½ to 6 inches) with higher R values may beproduced for insulation board purposes.

Top and bottom facers, 246 & 244, may be glass fiber mats according toone embodiment. The two facers may have roughly the same or similar matweight, or may have different mat weights. For example, in oneembodiment, top facer 244 is a relatively light weight or conventionalglass fiber mat while bottom facer 246 is a relatively heavy glass fibermat. In such embodiments, top facer 244 may have a mat weight rangingbetween about 1.2 lbs/100 ft² and 1.8 lbs/100 ft², while bottom facer246 has a mat weight ranging between about 1.4 lbs/100 ft² and 3 lbs/100ft². In a specific embodiment, bottom facer 246 has a mat weight ofabout 2.1 lbs/100 ft².

The thicknesses of the facers may vary as well. For example, top facer244 may have a thickness of about 0.025 inches or less while bottomfacer has a thickness of up to about 0.30 inches or more. In otherembodiments, both top facer 244 and bottom facer 246 may be relativelyheavy thick glass fiber mats. Conventional foam boards typically do notinclude facer having such mat weights and thicknesses due to theincreased cost and weight of the resulting roofing board.

The bottom facer 246 of foam board 242 may be coated with a heavycoating of the mineral based material. According to one embodiment, aheavy coating may be a coating having a coating weight of at least 10lbs/100 ft² (i.e., 0.10 lbs/ft²). According to another embodiment, aheavy coating may be any coating having a coating weight of at least 14lbs/100 ft² (i.e., 0.14 lbs/ft²). Top facer 244 may also be coated withthe mineral based coating or another material. A heavy coating asdescribed herein may be applied to the top facer, or in someembodiments, a lighter coating may be applied. The light coating may beany coating having a coating weight of less than 10 lbs/100 ft² (i.e.,less than 0.10 lbs/ft²), or in other embodiments, a coating weight ofless than 14 lbs/100 ft² (i.e., less than 0.14 lbs/ft²). In a specificembodiment, a continuous coating of the mineral based material isapplied to bottom facer 246 so that roofing board 240 has a coatingweigh to between about 14 and 30 lbs/100 ft², or more commonly betweenabout 18 and 21 lbs/100 ft². The thicker and heavier glass fiber matsdescribed above may allow the heavier mineral based coating to beapplied to the bottom facer 246. In other embodiments, both top facer244 and bottom facer 246 may include heavy mineral based coatings. Insome embodiments, foam board 242 may require a top and bottom facer, 244and 246, to prevent curling of the foam board 242 when exposed to heat.

The heavier and thicker bottom facer 246 having the heavy mineral basedcoating may be positioned adjacent a roof deck to limit the air flow tothe underlying roof deck and thereby suffocate a fire or prevent flamespread. The heavy coated bottom facer 246 and/or top facer 244 enablethe roofing board 240 to pass the UL 790 Class A test. These facers mayminimize shrinkage of the foam board core 242 when exposed to a fire'sheat and/or flame and thereby minimizing the formation of any gaps orvoids through which air can flow. The heavily coated foam compositeboards may not require the use of a fire retardant, although a fireretardant may be used in some embodiments, which may reduce the amountof the mineral based material that needs to be applied.

The heavy coated facer or facers may limit airflow regardless of thethickness and/or foam density of foam board 242. Thus, these facers maybe used for virtually any foam board to enable the boards to pass the UL790 Class A tests. Further, although possible, it is not necessary toface a foam board 242 on both sides with a heavy coated glass mat toenable the foam board 242 to pass the UL 790 Class A test. Rather,facing a bottom surface that is positioned adjacent to a roof deck isnormally all that is needed to enable passage of the test. Stateddifferently, a light or standard weight coated glass facer may be usedon a top surface that is ultimately exposed to a flame or the burningbrand. In this manner, costs and/or the weight of the resulting roofingboard 240 may be minimized. Expensive fire resistant fillers likeAluminum Tri-Hydrate, Borax, and the like, are also not required toenable the roofing board to pass the UL 790 Class A test, which mayprovide further cost savings.

Table 2 below shows UL 790 Class A burning brand test results forvarious foam board compositions. As shown in Table 2, standard foamcomposite board having light or standard weight facers failed the test,usually prior to the brand being 100% consumed and within the first 20minutes of the test. In contrast, foam composite boards having a heaviercoated glass facer (CGF) on the bottom surface or on both surfaces,passed the test. In each case the brand was 100% consumed and only in 1case did the test require the full 90 minutes allowed. The heaviercoated glass facer allowed the foam boards to pass the test regardlessof foam density, which ranged from 1.8 pcf to 6 pcf, and regardless offoam thickness, which ranged from ¼ inch to 2 inches.

TABLE 2 UL 790 Class A burning brand test results. Foam Brand Time to NoTime to Flame Foam Composite Board Density Consumption Smoke UnderneathDeck Test Conditions ¼″ thick, standard 6 pcf 80% NA at 10 min. FAILClass A Brand, small Coated Glass Facers scale E108 test (CGF) on bothsides deck, 1″ slope ¼″ thick, standard 6 pcf 90% NA at 21 min. FAILClass A Brand, CGF on both sides UL790, 0.5″ slope ¼″ thick, heavier CGF5 pcf 100% 37 min. No PASS Class A Brand, on both sides UL790, 1″ slope¼″ thick, heavier CGF 5 pcf 100% 39 min. No PASS Class A Brand, on bothsides UL790 3″ slope ¼″ thick, heavier CGF 5 pcf 100% 50 min. No PASSClass A Brand, on bottom side, UL790 3″ slope standard CGF on top side¼″ thick, heavier CGF 5 pcf 100% 87 min. No PASS Class A Brand, onbottom side, UL790 3″ slope standard CGF on top side ¼″ thick, heavierCGF 5 pcf 100% 44 min. No PASS Class A Brand, on bottom side, UL790 3″slope standard CGF on top side ¼″ thick, heavier CGF 5 pcf 100% 90 min.No PASS Class A Brand, on bottom side, UL790 3″ slope standard CGF ontop side 2″ thick, standard CGF 1.62 pcf  25% NA   6 min. FAIL Class ABrand, small on both sides scale E108 test deck, 1″ slope 1″ thick,standard CGF 1.8 pcf  15% NA   4 min. FAIL Class A Brand, small on bothsides scale E108 test deck, 1″ slope 1.5″ thick, heavier CGF 1.8 pcf 100% 36 min. No PASS Class A Brand, small on both sides scale E108 testdeck, 1″ slope 1.5″ thick, heavier CGF 1.8 pcf  100% 46 min. No PASSClass A Brand, small on bottom side, scale E108 test standard CGF on topdeck, 1″ slope side

Having described several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theinvention. Additionally, a number of well-known processes and elementshave not been described in order to avoid unnecessarily obscuring thepresent invention. Accordingly, the above description should not betaken as limiting the scope of the invention.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimits of that range is also specifically disclosed. Each smaller rangebetween any stated value or intervening value in a stated range and anyother stated or intervening value in that stated range is encompassed.The upper and lower limits of these smaller ranges may independently beincluded or excluded in the range, and each range where either, neitheror both limits are included in the smaller ranges is also encompassedwithin the invention, subject to any specifically excluded limit in thestated range. Where the stated range includes one or both of the limits,ranges excluding either or both of those included limits are alsoincluded.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise. Thus, for example, reference to “a process” includes aplurality of such processes and reference to “the device” includesreference to one or more devices and equivalents thereof known to thoseskilled in the art, and so forth.

Also, the words “comprise,” “comprising,” “include,” “including,” and“includes” when used in this specification and in the following claimsare intended to specify the presence of stated features, integers,components, or steps, but they do not preclude the presence or additionof one or more other features, integers, components, steps, acts, orgroups.

1-5. (canceled)
 6. A rooting board comprising: a roofing board; and amineral based material coating on one or more major surfaces of theroofing board, the mineral based material coating having a coatingweight of at least 0.10 lbs/ft2, the coating being sufficientlyimpervious to limit air flow through the roofing board to enable theroofing board to pass the UL 790 class A tests.
 7. The roofing board ofclaim 6, wherein the roofing board does not include a fiber mat facer.8. The roofing board of claim 6, wherein the roofing board furthercomprises a glass mat facer applied to one or more major surfaces; themineral based material being applied to each glass mat facer.
 9. Therooting board of claim 8, wherein the roofing board comprises two glassmat facers applied on opposite major surfaces of the roofing board,wherein a first glass mat facer comprises a coating weight of at least0.10 lbs/ft2 of the mineral based material, and wherein a second glassmat facer a coating weight of less than 0.10 lbs/ft2 of the mineralbased material.
 10. The roofing board of claim 9, wherein the firstglass mat facer comprises a first glass mat weight, and where the secondglass mat facer comprises a second glass mat weight less than the firstglass mat weight.
 11. The roofing board of claim 8, wherein each glassmat facer has a weight of at least 1.4 lbs/100 ft2.
 12. The roofingboard of claim 6, wherein mineral based material comprises between about25% and 50% water and between about 50% and 75% of a composition ofsolid materials, and wherein the coating is approximately 100% solidsafter drying.
 13. The roofing hoard of claim 12, wherein the compositionof solid materials comprises a combination of a first filler materialand a second filler material.
 14. The rooting board of claim 12, whereinthe first filler material comprises: calcium carbonate, perlite, clay,or gypsum; and wherein the second filler material comprises: clay, mica,talc, expanded perlite fines, flumed silica, fly ash, fiber glass,vermiculite, titanium dioxide, or zinc oxide.
 15. The roofing board ofclaim 6, wherein the mineral based material coating has a coating weightof at least 0.14 lbs/ft2.
 16. The roofing board of claim 11, wherein themineral based material coating has a coating weight of between about0.18 lbs/ft2 and about 0.21 lbs/ft2.
 17. The roofing board of claim 6,wherein the mineral based material comprises calcium carbonate and anacrylic binder.
 18. The roofing board of claim 6, wherein the roofingboard does not include a fire retardant.
 19. The roofing board of claim6, wherein the roofing board is between about ¼ inch thick and 6 inchesthick.
 20. The roofing board of claim 19, wherein the roofing boardcomprises a density between about 1.5 lb/ft3 and about 12 lbs/ft3. 21.The roofing board of claim 6, wherein the roofing board comprises one ormore of the following materials: wood fibers; perlite; polyisocyanurate;polystyrene; extruded polystyrene; cellular glass; pressed recycledpaper; or particle. 22-24. (canceled)
 25. A method of manufacturing aroofing board comprising: providing a roofing board, applying a mineralbased material to at least one major surface of the rooting board, themineral based material being applied such that the roofing boardcomprises a coating weight of at least 0.10 lbs/ft2, the coating beingsufficiently impervious to limit air flow through the roofing board toenable the roofing board to pass the UL 790 class A tests. 26.(canceled)
 27. The method of claim 25, further comprising: applying aglass mat to at least one major surface of the roofing board such thatthe at least one major surface is faced with the glass mat; and applyingthe mineral based material to the faced glass mat surface of the roofingboard.
 28. The method of claim 27, further comprising: applying a secondglass mat to the other major surface of the roofing board such that bothmajor surfaces of the roofing board are faced with a glass mat; andapplying a coating to the other faced glass mat surface of the roofingboard, the coating being applied so as to comprise a coating weight ofless than 0.10 lbs/ft2.
 29. The method of claim 28, wherein the facedglass mat comprising the coating weight of at least 0.10 lbs/ft2 faces aroof deck. 30-31. (canceled)
 32. The roofing board of claim 6, whereinthe roofing board comprises perlite.